I've just been spending spare hours since Thursday writing the app, so let me know if you find a bug. It supports Android 2.1 and above, but may require you to go enable Settings: Applications: Unknown sources -- I'm not hosted on the Android Market.
Enjoy, and let me know what you think.
Update: it's out for 3o seconds and already I spotted a bug. Version 1.1 released.
Update: Version 1.2 is out. Now there is a reply button in addition to retweet. Yay!